Sunday, December 30, 2012

Charlie Duke catches Apollo 16 commander John Young as he salutes Old Glory in mid-jump, demonstrating the Moon's low gravity. See the original at NASA's Apollo Lunar Surface
Journal, HERE (MET: 120:25:42 - AS17-113-18339).

"He is off the ground about 1.45 seconds which, in the lunar gravity
field, means he launched himself at a velocity of about 1.17 meters per second
and reached a maximum height of 0.42 meters. Although the suit and backpack
weighed as much as he did his total weight was only about 65 pounds (30
kg). To get to this height he only had to bend his knees slightly and push up with his legs." Video Clip
( 3 min 21 sec 0.9 Mb RealVideo or 30 Mb MPEG )
[NASA].

Ben Evans
AmericaSpace

In the days before his first mission into space, way back in March 1965, John Young was asked by a journalist if he minded flying into orbit with the fiery Virgil ‘Gus’ Grissom as his Gemini 3 crewmate. Without blinking, the 34-year-old Young replied: “Are you kidding? I’d go with my mother-in-law!” It was an indicator not only of Young’s intense dry wit, but of his equally intense devotion to the exploration of the final frontier – an exploration which consumes 400 pages in his long-awaited memoir, Forever Young, co-authored with Auburn University history professor and Neil Armstrong biographer James R. Hansen.

Long-awaited because Young has earned himself a reputation over the past five decades which cannot be surpassed. True, there are astronauts who have flown more times into space than him. True, there are other astronauts who have walked on the Moon, besides him. True, there are astronauts who have commanded more missions and flown longer in space than him. But for sheer longevity within the astronaut business, John Watts Young is unrivaled. Selected as a member of NASA’s second intake of spacefarers in September 1962 – an intake which former chief astronaut Deke Slayton once described as “probably the best all-around group ever put together” – he spent more than 40 years with NASA and flew six times, across three separate programs: Gemini, Apollo and the Shuttle. Even Jerry Ross, who became the first human to record a seventh voyage into space, has described Young as his hero.

Saturday, December 29, 2012

A portion of the floor of Nicholson crater on the mountainous rings surrounding Mare Orientale, is swept away by the pressure front delivered by a smaller and much more recent impact. From LROC Narrow Angle Camera (NAC) observation M140468128R, centered on 26.103°S, 274.952°E; 612 meter wide field of view captured at 51 cm resolution during LRO orbit 5834, September 30, 2010 [NASA/GSFC/Arizona State University].

Hiroyuki Sato
LROC News System

The opening image is of a surface swept by the ejecta of an unnamed 300 meter diameter fresh crater that is located about 1.8 km to the south. This area is on the floor of Nicholson crater (about 38 km in diameter), that is at the southeast edge of Orientale basin.

As you can see in the next NAC context image, the higher reflectance rays extending radially outward from the parent crater highlight the path of ejecta. But the actual area of the continuous ejecta deposition is difficult to detect from the reflectance contrasts alone. When a single ejecta particle hits it churns up the subsurface revealing brighter immature material from below.

A wider, approximately 1.7 km view of the opening field of view (white box) shows the young unnamed crater on Nicholson crater's floor immediately to the south [NASA/GSFC/Arizona State University].

Among the numerous rays, high reflectance spots can be found at the north side of multiple small craters (~40 m in diameters). Some appear to be pre-existing craters that had their rims eroded by the ejecta, thus revealing brighter immature material. The small craters with very bright ejecta may be the result of large blocks of ejecta that were thrown out at a shallow angle and plowed up the substrate also revealing immature material.

Dramatic context for Nicholson crater, situated on the peak ring mountains, second row out from the interior basin of Mare Orientale, is seen in this false color orthographic projection of the LROC Wide Angle Camera Digital Terrain Model, centered on the 300th meridian east [NASA/GSFC/DLR/Arizona State University].

The overall effect of low angle ejecta spraying across the surface is similar to blowing dust on the Earth that erodes the landscape. Of course the Moon has no atmosphere, so the sand blasting effect lasts for a mere seconds rather the slow cumulative effect of wind-blown dust on the Earth.

Explore the newly disturbed surface on the Moon in full NAC frame yourself, HERE.

Wednesday, December 26, 2012

The prominent, very distinctive central peaks of farside Tsiolkovskiy crater, from a new, scaled mosaic of the left and right frames of LROC Narrow Angle Camera (NAC) observation M1098059280, spacecraft orbit 14176, July 27, 2012; resolution between 4.6 and 5.3 (top) meters per pixel, captured 87.66 km over 20.44°S, 121.42°E, a point over 200 km west of the highest promontory. Larger versions available HERE [NASA/GSFC/Arizona State University].

Joel Raupe
Lunar Pioneer

Each quarterly release of LROC data to the Planetary Data System (the twelfth, on December 15, covers the three months between mid-June and September), is not really complete until the KML index emerges, for viewing through Google Earth's lunar simulation.

The KML data are a fast and intuitive way yet to search directly for LROC NAC images, especially those with exceptionally high slew angles, the few oblique images. And the latest KML files appeared on the Massachusetts Institute of Technology servers December 21.

Since the very first grainy, misunderstood images of the Moon's far side were returned to Earth by the Soviet Union in 1959, Tsiolkovskiy immediately stood out, strongly underscoring the remarkable differences between the tidally locked hemispheres. LROC Wide Angle Camera (WAC) context view of the most conspicuous mare-flooded surface on the lunar farside, 185 km Tsiolkovskiy crater [NASA/GSFC/Arizona State University].

The oblique views are rare. Off nadir NAC observations are of a lower scientific value, perhaps, than the job of completing the high-resolution photography of the entire Moon, a goal the LROC team is closing in on. My favorite targets for these oblique views are never in the new batches, but there's always one or two that are breathtaking and unexpected.

Last September LROC's 11th release included an oblique look into the interior of Antoniadi, for example, that was then included in our post highlighting oblique views of Engel'gardt heights. Antoniadi, as it turns out, figures prominently in the aforementioned landing site study. Follow-up posts on that Eratosthenian crater, well inside the very ancient South Pole-Aitken basin, are in preparation.

Among the new, few oblique views that really stand out in the twelfth release is an off-nadir view of the central peaks of Tsiolkovskiy, shown up above. The complete field of view here is a highly re-sampled (less than 8 percent) version of what was originally a 6204 by 8955 mosaic (of LROC NAC M1098059280LR, swept up last July). It's reduced down to 580 x 800, or the maximum size allowable in a blogger post.

Because we derive vast amounts of valued-added imagery, in an image-intense subject of study, this last limitation has become a nagging problem we would like to solve.

Quarter resolution view of the LROC NAC mosaic shows some of the glory of the wider view, the eastern range and summit, as well as some of the considerable slumping of the degraded northern section of Tsiolkovskiy central peak [NASA/GSFC/Arizona State University].

We would welcome recommendations and/or reviews of image hosting sites, most especially those that do not presume to arbitrarily substitute photography with lossy resampling. Meanwhile, a planned migration to a new host for this website has been delayed yet again.

A virtually full resolution view of a high promontory of the Tsiolkovskiy central peak, suffering from a foreshortening affect, partly the result of simple distance and the high lateral motion of the LRO spacecraft, more 200 kilometers away. Like a more dramatic LROC NAC view of the high place on the central peaks of Tycho, this view seems to show a large boulder sitting near its top, likely a rock that emerged from the upthrust after considerable mass wasting [NASA/GSFC/Arizona State University].

Perhaps the best off-nadir view of the central peak of Tsiolkovskiy crater, prior to this latest oblique LROC NAC observation, from among the HDTV stills of the crater captured by Japan's SELENE-1 (Kaguya) orbiter in 2008. The view is from well to the north [JAXA/NHK].

Like the oblique LROC NAC mosaic of the Moon's highest elevation at Engel'gardt, discussed here in early October, this latest view of Tsiolkovskiy took place while the area of interest was under a high Sun, and from a great distance. Thus the raw result is of low contrast, the details of relief given over to raw albedo. That, and the apparent lateral motion through a field of view made small by distance, results in a less than perfect aesthetically pleasing result. We will take what we can get before continuing with the work of putting together raw illustrations needed to offer posts about the LUNAR landing site study.

Another 'full-resolution' first look at the new Tsiolkovskiy central peak NAC mosaic, this section near the southern base, a good illustration of the affects of foreshortening, and lateral speed through a narrow window, and over a bright Sun-Subject-Spacecraft phase angle. Though their trails are not individually seen, the subject and scene shown above are near to the area shown at much higher resolution (from overhead) discussed in the LROC Featured Image post "Weaving boulder trails on the Moon," last July 11 [NASA/GSFC/Arizona State University].

Aristarchus in one sweep, an orbital swath ultimately stitched into a four-orbit mosaic, shows one of the most photographed of the complex lunar craters in unusually muted tones. Because Aristarchus is unusually bright, the reason it is most often cited as the reported location of Transitory Lunar Phenomena, fast LROC low-orbit photography allows an unwashed-out appreciation of its topographic detail. Full-width strip of LROC Wide Angle Camera (WAC) observation M162622850CE, (604nm), LRO orbit 9099, June 13, 2011; resolution 56.85 meters at a morning angle of incidence of 79° from 40.77 km [NASA/GSFC/Arizona State University].

Strip from the four sequential LROC WAC orbital observations mosaic shows young Aristarchus nested on the southeastern heights of Aristarchus plateau, together with the Cobra Head and much older, mare-flooded companion Herodotus to the west. The youngest mare surface on the Moon yet identified, estimated to be a mere 1.1 billion years old, is situated at the southern end of this field of view. Despite it's relative youth, that surface is older than Copernican-age Aristarchus, so the crater cannot be its source [NASA/GSFC/Arizona State University].

Artist’s illustration of the EFT-1 Orion in orbit, following a planned launch atop a Delta-IV Heavy booster in September 2014 [NASA].

Ben Evans

AmericaSpace

In less than two years’ time, NASA intends to loft its first unmanned Orion spacecraft on the long-awaited Exploration Flight Test (EFT)-1 mission atop United Launch Alliance’s gigantic Delta IV Heavy booster. The mission, which will rise to a maximum altitude of 3,600 miles—the highest a human-capable vehicle has flown since the end of the Apollo era—will serve to wring out many of Orion’s systems in readiness for its first Exploration Mission in late 2017. NASA took one step toward the EFT-1 goal yesterday (Thursday), by completing the latest in a series of parachute drop tests of a mock-up vehicle at the US Army’s Yuma Proving Ground in Arizona. The test confirmed that Orion could land safely even if one of its two parachutes failed to open during the critical final stages of descent.

Aristarchus crater, one of many fascinating exploration destinations on the Moon: young, highly reflective, rugged, and colorful! Look at the shades of grey in the small central peak, an inviting tapestry of geologic diversity!

Looking up and over to the east, on the steep walls of the crater, observe the streaks marking ejecta leaving the crater. The shades of grey in the streaks likely trace back to the diverse stratigraphy seen in the central peak. Imagine a future lunar explorer traversing around the base of the 300 meter tall central peak while collecting samples. There are at least three different distinct shades of grey seen on the steep slopes, perhaps more? Though climbing to the top and walking the ridge would afford a magnificent view, simply collecting rocks along the base would suffice from a geologic viewpoint.

The next logical step is to collect samples along the east and southeast wall of the crater. Do the distinct rays seen trace back to the layers seen in the central peak? What about the enigmatic reddish brown material just on the southeast flank? The geology of the Moon is rich and complicated!

From LROC WAC color images you can see that the gray streaks show up as distinct color anomalies, color due to variations in rock type. The area has long been known to be among the reddest spots on the Moon - meaning its reflectance strongly increases from short to long wavelengths. In the WAC color image below, you can see the distinct red-hued region, which is largely blanketed by the glass-rich products of explosive volcanic eruptions. This area is surrounded by bluer terrain, which formed when titanium-rich (at least it is thought that titanium is in these rocks) lava flowed across the surface and flooded the area, forming a portion of Oceanus Procellarum. In both of the WAC context images, you can see Vallis Schröteri, a canyon-like feature known as a sinuous rille, through which the lava once flowed.

At the intersection of this amazingly diverse region, the Aristarchus impact event gives us a three-dimensional look into the plateau. The central peak of Aristarchus, which uplifted material from great depth, is thought to in part sample the anorthositic material that makes up the lunar highlands, and portions of the southeastern wall and rim, which are seen in today's oblique NAC view of the crater, are thought to be rich in olivine.

The bounty of geologic processes that came together to produce this complex region makes it a high-priority target for future exploration. The geologic interest is not the end of the story. Pyroclastic deposits there may contain valuable resources to be mined by future explorers.

The lower-right half of this image is the relatively rough surface of the basin wall. The smoother part in the upper left corresponds to the mare basalt deposit that extends ina north-south direction (see WAC context image at the bottom of this post).

Just below in the NAC context image, there is a trench on the mare surface about 650 meters in width. The slope materials slid down the trench, resulting in a sharp distal edge.

Determining the origin of this trench is not easy from this image alone, but it must have been formed after mare basalt was deposited as a flat surface. Later material from the wall slid downslope and partially covered the bottom of the trench.

The wider NAC context view of the opening image, showing the bottom edge of the slope and trench, in a field of view about 1.2 km across [NASA/GSFC/Arizona State University].

Small slumps of highland material overlying the edge of mare are common on the Moon. Since the mare were deposited as very fluid magma, the lava's extent was confined by pre-existing highland topography. Similar to how hills and mountains confine lakes on the Earth. Back to the Moon, over time the confining highland hills slump and slide onto the mare, slowly blurring the highland-mare boundary. In this case older material ends up on top of younger material (reverse stratigraphy). Of course the slump deposit itself is younger, however the age of the rocks and soil particles that make up the slide are older than the age of the mare basalts. We do not know the exact process and the timescale of such slope degradations. How was the slide triggered? Perhaps slide is not the best term. It may be that very slowly over time individuals particles are moved downslope (creep) by the extreme night-to-day temperature swings on the Moon. Or perhaps a true landslide was triggered by a nearby impact event that set off moonquakes. A geologist on the ground could collect small-scale measurements and determine the exact cause, or causes (perhaps both mechanisms were at work). Such analyses will be important as future explorers determine the best places to build structures and roads.

Eastern portion of Orientale basin in an LROC Wide Angle Camera (WAC) monochrome mosaic (100 meters per pixel). Image center is 18.63°S, 275.66°E, covering about 135 km across. The blue box and the white arrow indicate the area within the full NAC frame and the area shown at high resolution, respectively [NASA/GSFC/Arizona State University].

Explore the sharp slope edges invading the trench and other features in full NAC frame yourself, HERE.

Thursday, December 20, 2012

A small unnamed crater sits on the rim of a larger crater which, in
turn, is itself nested on the rim of farside pre-Nectarian crater
Buisson. LROC Narrow Angle Camera (NAC) observation M1107532088RE,
spacecraft orbit 15502, November 14, 2012; field of view roughly 1000
meters, resolution 1.05 meters per pixel [NASA/GSFC/Arizona State
University].

Drew Enns
LROC News System

The law of superposition is one of the earliest geologic laws, based on the observations of Danish scientist Nicholas Steno.

Originally formulated to describe relative ages of sedimentary rock units, the law of superposition works just as well on the Moon to describe relative age relationships of separate lunar terrains and craters.

What are the relative ages of the different craters in today's Featured Image?

LROC Wide Angle Camera (WAC) mosaic of Buisson, context for the field of view above, showing the small crater at high resolution above (red box). Additionally, a relatively small crater sits on the rim of ancient Buisson, located at 1.42°S, 112.96°E. Field of view 100 km [NASA/GSFC/Arizona State University].

In today's Featured Image, we have three separate craters. Buisson crater is the largest at 57 km, with an approximately 4 km wide unnamed crater on its rim.

Zooming in further, we see an even smaller crater, about 110 meters wide, in the 4 km crater rim. The superposition of these craters gives us a relative age relationship with the 110 m crater the youngest, followed by the 4 km crater, and finally Buisson crater.

In the lower right, South Massif casts a long evening shadow across the mare basalt flooded Taurus Littrow valley. Note the sharp boundary of the flat mare against the slopes of the Sculptured Hills in the background, similar to a lake shoreline, revealing the very fluid nature of the lava when it filled the valley. Your eye is drawn to the sharp line snaking across the bottom of the image. Note how this ridge traverses across the valley floor and up onto the lower slopes of North Massif (lower left). Astonishingly this feature is a large, young fault: imagine the ground in the foreground being pushed to the east and the crust buckling, a whole section was pushed up and onto the back side of the fault (low angle thrust fault). This step in the valley floor was the result of large scale contractional forces pushing the crust together. The landform created by this type of thrust fault is called a lobate scarp, this one is named the Lee Lincoln scarp. The Lee Lincoln scarp has the distinction of being the first and only extraterrestrial fault to be explored by humans. Astronauts Harrison Schmitt and Gene Cernan actually drove the Lunar Roving Vehicle (LRV) up and over this ridge during their three day exploration of the valley.

Apollo 17 commander Gene Cernan works next to the LRV at Station 3, near Lara crater, (see labeled detail below). AS17-138-21168[NASA/Harrison Schmitt].

Where the Lee Lincoln scarp stretches into the highlands of North Massif, it abruptly changes directions and extends along slope far beyond the Apollo 17 landing site (black arrows on full NAC image). The Lee Lincoln scarp is one of a number of such tectonic landforms that were only found in the high resolution Apollo Panoramic Camera images that covered part of the lunar equatorial zone. In LROC NAC high resolution images, lobate scarps have been discovered across the Moon at all latitudes (Watters and coworkers, 2010). The pristine appearance of the lobate scarps and the fact that the features cut across young, small-diameter craters are evidence that the scarps formed recently, more recently than the young craters they deform. The globally distributed population of lobate scarps is an indication that contractional forces are acting on the lunar crust as a result of slow cooling and shrinking of the still hot interior of the Moon.

West to east Oblique labeled - Central portion LROC NAC oblique showing
significant features visited by the Apollo 17 crew, LM is the Lunar
Module. North is to the left, and south is to the right. The distance
along Lee Lincoln scarp from the shadow to North Massif is 8 km, M1096343661LR [NASA/GSFC/Arizona State University].

It was forty years ago today that the Apollo 17 crew splashed down in the Pacific Ocean, ending our first period of human exploration of the Moon. The extensive measurements beamed back from LRO every day are setting the stage for the next era in robotic and human exploration of the Moon. Where would you go on the Moon to continue the work of the Apollo crews?

Tuesday, December 18, 2012

An outcrop exposed in the central peak of Petavius crater revealed in
large fracture. From LROC Narrow Angle Camera (NAC) observation M1107889912LE,
captured at 0.84 meters per pixel in LRO orbit 15552, November 18,
2012; field of view approximately 840 meters across [NASA/GSFC/Arizona
State University].

Drew EnnsLROC News System

Petavius crater, a 177 km crater located at 25.28°S, 60.63°E, is one of an uncommon class of craters that have been modified by post-impact processes. What process could have produced the system of fractures that cut the floor, known as Rimae Petavius? Volcanism is the likely cause. Small patches of mare basalt exist in the north and south extents of the crater floor, which help cement this hypothesis. But unlike other mare filled craters, Petavius crater has only small patches of basalt.

Why did Petavius crater end up with such an extensive fracture system?

Context the LROC Featured Image, 100 km-wide field of view includes the cluster of the Petavius central peaks, composed of material tossed up from great depth when the crater formed in the lower Imbrium age, 3.9 billion years ago. Some darker basaltic material
is in the northeast and southeast corners of this image, likely opportunistic intrusions of molten material that "seeped" to the surface following some global event, like the basin forming impact that formed Mare Orientale [NASA/GSFC/Arizona State University].

One hypothesis is that the fractures occurred as a result of volcanic modification. Uplift of the crater floor would occur as magma intruded beneath the floor and fracturing developed as the floor was pushed up. Because Petavius crater was not flooded completely, the fractures were never covered by basalt. The harder question is why is Petavius crater not flooded with basalt?

It is possible Petavius crater did not witness the same style of eruption as elsewhere on the Moon. Or maybe the magma underneath Petavius crater was not buoyant enough to completely flood the surface. Finally, it may simply be that the magma source region was relatively small, and thus only a modest amount of basalt was erupted.

Explore more of Petavius crater in the full LROC NAC observation HERE.

Petavius is a familiar telescopic landmark from Earth, after the Moon is 3 days old (or 2 days after a Full Moon), though fresher, rougher and less optically mature bright ejecta from smaller neighboring craters like Stevinus and Petavius B tend to overwhelm the scene as the region approaches mid-day. The simulated phase above shows the location of Petavius in relation to the Moon's appearance tonight. Virtual Moon Atlas v.6 using LROC WAC 100 meter textures [VMA].

Monday, December 17, 2012

Ebb and Flow Finale - The two GRAIL spacecraft, Ebb and Flow, as
imaged by the LROC NAC in lunar orbit at different times (A on 7th
October, B on 8th October 2012) [NASA/GSFC/Arizona State University].

The Gravity Recovery and Interior Laboratory (GRAIL) spacecraft are nearing the end of their mission. Launched in September of 2011, these two intrepid spacecraft have mapped the lunar gravity field in unprecedented detail, a boon for lunar scientists! However, they have expended their fuel reserves, and both will make controlled crashes onto the lunar surface today.

During their one year mission the GRAIL spacecraft often came close to LRO, in some cases the distance was less than 10 km! On 7 October 2012 as GRAIL A passed within 11 km, LRO pitched forward 30° and and rolled 16° to snap an image as the Sun glinted off Ebb's solar panels and main deck. The next day a similar opportunity presented itself and LROC imaged GRAIL B.

GRAIL A sketch - Rough sketch showing orientation of GRAIL A
(Ebb) as seen from LROC on 7 October 2012, dimensions are in cm, the
roll angle was 16° (not 15°) [A. Boyd, ASU].

In both instances the orbit track of the GRAIL spacecraft was angled by 120° relative to LRO's orbit, and the twin spacecraft passed below LRO in the lunar night. Since the LROC NAC is a line scanner, it builds up an image line-by-line, and depends on the spacecraft to orient its CCD sensor perpendicular to the ground path. In the case of the GRAIL images, LRO was not reoriented so the images are distorted, the slews added to the distortion. Using spacecraft ephemeris, the distorted image of GRAIL was corrected back to a normal geometry.

Ebb and Flow will impact a 2400 meter (7874 feet) tall mountain, about 450 km from the lunar north pole, at approximately 2:28 PM PST, (22:28:40 & 22:29 UT)Monday 17 December 2012. Antennas on Earth will be tracking both spacecraft until the moments of impact. The last few orbits will be very low, and may provide some extremely high resolution gravity profiles. Just before impact, the two spacecraft will come astonishingly close to a ridge between 71°N and 72°N (see WAC mosaic further below).

Planned impact site for the GRAIL twin orbiters, 20 seconds apart, 2229 UT, 17 December. Field of view roughly 17 km across, from a mosaic of the left and right frames from LROC Narrow Angle Camera (NAC) observationM188437321LR, LRO orbit 12830, April 7, 2012 [NASA/GSFC/Arizona State University].

GRAIL impact zone from global Chang'E-2 60 meter mosaic [CNSA/CLEP].

The two GRAIL spacecraft are identical, and each has a mass (without fuel) of about 130 kg (287 lbs). When they hit the mountain at about 1.6 km/sec (3579 mph), they will each make small impact craters, about a meter across. The craters will be too small to resolve with LROC, but the bright ejecta around those craters, which should be a few meters across, might be visible. Optimal lighting for future LROC imaging of the GRAIL craters will occur next March through April (2013).

LROC WAC mosaic of GRAIL Impact Site - Ebb and flow will come in
from the south, fast and low, and impact the tall mountain indicated
withred dot. A few moments before impact they streak just above a high
ridge. Imagine the view! LROC WAC mosaic sampled at 160 meters per pixel
[NASA/GSFC/Arizona State University].

Sunday, December 16, 2012

The 8000 meter wide pyroclastic vent high on the second outer ring of Mare Orientale, at very high resolution, has nearly invariably been in shadow, or the LRO spacecraft has been at lower altitude and too close to catch this breathtaking view in one take. As it is, the full observation was repeated in sequential orbits, the makings of a spectacular stereo 3D anaglyph. From a mosaic including both the left and right frames of LROC Narrow Angle Camera (NAC) M1099502843, orbit 14378, August 13, 2012; resolution 0.75 meters from 72.12 km [NASA/GSFC/Arizona State University].

The Lunar Reconnaissance Orbiter Camera (LROC) team at Arizona State University, and investigation teams overseeing the other instruments on-board the robust LRO platform, are once again on time with their 12th quarterly release to the Planetary Data System (PDS). Its another impressive store, with more data gathered over three months than most deep space missions sweep up in an entire tour. All together, the LRO mission has again broken its own record, one unlikely to be surpassed for many years. LRO has returned more data than all present and past deep space missions combined.

To a widespread, devoted and grateful group unashamed to call themselves "lunatics," Christmas has arrived early once again this year.

Far to the northeast of the more familiar heart of the Reiner Gamma albedo swirl (and magnetic anomaly) in Oceanus Procellarum, the bright but thin layer of optically immature regolith meanders up into the Marius Hills. The higher altitude assumed by the LRO mission this year allowed the diffuse contact region to be photographed in one observation, under the same lighting conditions. The LROC Wide Angle Camera 100 meter global mosaic is used as context for that area, swept up in the NAC observation below [NASA/GSFC/Arizona State University].

Still at high resolution, the physical relationship at the surface between the Reiner Gamma swirl and the Marius Hills volcanism can be studied under similar lighting condition, and in one take, in this LROC NAC mosaic. LROC NAC M1099209032LR, orbit 14337, August 10, 2012; resolution in the original 0.98 meters from 118.85 km, angle of incidence 40.15° [NASA/GSFC/Arizona State University].

"The 12th LROC Planetary Data System release includes images acquired between June 16 to September 15," according to the announcement, posted by LROC team member Ernest Bowman-Cisneros.

"To date," Bowman-Cisneros writes, "the LROC Team has delivered 893,493 LROC images and over 8,653 derived (RDR) data products to the NASA Planetary Data System. The complete LROC PDS archive can be accessed via the URL http://lroc.sese.asu.edu/data or a search for specific images or mosaics can be made using the LROC WMS browser. Also be sure and try out QuickMap!"

The anatomical mix of dark and relatively bright featured tossed up by simple craters impacting the Marius Hills can also be examined from the unique perspective presented in the LROC NAC oblique images, this one being the first we stumbled across, a brief study of the shield volcano's interior. LROC NAC M1096851065LR, LRO orbit 14007, July 13, 2012 [NASA/GSFC/Arizona State University].

Friday, December 14, 2012

"To mark the 40th anniversary of the last human footsteps on the moon," Andrew Chaikin, author A Man on the Moon (Penguin, 2007), looks back "at Apollo 17's explorations, and I explain why I believe the moon is the solar system's "jewel in the crown," beckoning us to return.

GRAIL's Final Resting Spot. These maps of Earth's moon
highlight the region where the twin spacecraft of NASA's Gravity
Recovery and Interior Laboratory (GRAIL) mission will impact on Dec. 17,
marking the end of its successful endeavor to map the moon's gravity.
The two washing-machine-sized spacecraft, named Ebb and Flow, will
impact an unnamed mountain above of 75°N. [NASA/GSFC/Arizona State University].

Pasadena (JPL) -- Twin lunar-orbiting NASA spacecraft that have allowed scientists to learn more about the internal structure and composition of the moon are being prepared for their controlled descent and impact on a mountain near the moon's north pole at about 2028 UT (5:28 p.m. U.S. EST) Monday, December 17.

Ebb and Flow, the Gravity Recovery and Interior Laboratory (GRAIL) mission probes, are being sent purposely into the lunar surface because their low orbit and low fuel levels preclude further scientific operations. The duo's successful prime and extended science missions generated the highest-resolution gravity field map of any celestial body, providing a better understanding of how Earth and other rocky planets in the solar system formed and evolved.

Perspective on the Moon at the estimated time of the GRAIL impacts, projected at 2229 UT, 17 December 2012. Waxing between New and First Quarter (4.58 days 26.8% illumination), the distance between Earth and Moon will be increasing at roughly 10 km per minute from 372,628 kilometers. In eastern North America, the Moon will have transited, riding low and west from overhead Only the best equipped observers can hope to observe the actual release of kinetic energy, an extremely fast flash, near the horn of the north-northwest limb [Virtual Moon Atlas].

"It is going to be difficult to say goodbye," said GRAIL principal investigator Maria Zuber of the Massachusetts Institute of Technology in Cambridge. "Our little robotic twins have been exemplary members of the GRAIL family, and planetary science has advanced in a major way because of their contributions."

Lunar Heritage Sites and GRAIL's Final Mile. This graphic
highlights locations on the moon NASA considers "lunar heritage sites"
and the path NASA's Gravity Recovery and Interior Laboratory spacecraft
will take on their final flight. Navigators on the GRAIL team have
designed an end of mission plan that rules out the extremely remote
possibility of either of the two GRAIL spacecraft impacting near any of
these historic locations. The Apollo 11, 12, 14, 16 and 17 landing sites
are indicated with green circles. The Surveyor sites are indicated with
yellow squares. The Soviet Union's Luna and Lunakhod landing sites are
indicated with red diamonds and red squares, respectively. The ground
track for the Ebb and Flow spacecraft during their final half-orbits is
shown in black. The maps are color-coded by topography. Red and white
indicate the high areas. Blue and violet indicate low areas
[NASA/JPL-Caltech].

The mountain where the two spacecraft will make contact is located near a crater named Goldschmidt. Both spacecraft have been flying in formation around the moon since Jan. 1, 2012. They were named by elementary school students in Bozeman, Mont., who won a contest. The first probe to reach the moon, Ebb, also will be the first to go down, at 2:28:40 p.m. PST. Flow will follow Ebb about 20 seconds later.

Both spacecraft will hit the surface at 3,760 mph (1.7 kilometers per second). No imagery of the impact is expected because the region will be in shadow at the time.

Ebb and Flow will conduct one final experiment before their mission ends. They will fire their main engines until their propellant tanks are empty to determine precisely the amount of fuel remaining in their tanks. This will help NASA engineers validate fuel consumption computer models to improve predictions of fuel needs for future missions.

"Our lunar twins may be in the twilight of their operational lives, but one thing is for sure, they are going down swinging," said GRAIL project manager David Lehman of NASA's Jet Propulsion Laboratory in Pasadena, Calif. "Even during the last half of their last orbit, we are going to do an engineering experiment that could help future missions operate more efficiently."

Because the exact amount of fuel remaining aboard each spacecraft is unknown, mission navigators and engineers designed the depletion burn to allow the probes to descend gradually for several hours and skim the surface of the moon until the elevated terrain of the target mountain gets in their way.

Ebb and Flow's Final Moments. These side-by-side, 3-D comparisons
depict the unnamed lunar mountain targeted by the NASA's Gravity
Recovery and Interior Laboratory (GRAIL) mission for controlled impact
of the Ebb and Flow spacecraft. They also include the ground tracks the
spacecraft are expected to follow into the lunar terrain. These graphics
were generated using data from the Lunar Orbiter Laser Altimeter
instrument aboard NASA's Lunar Reconnaissance Orbiter spacecraft. On the
left is the mountain with the ground track and mission termination
point for the Ebb spacecraft. On the right is the mountain, ground track
and mission termination point for the Flow spacecraft
[NASA/JPL-Caltech/MIT/GSFC].

The burn that will change the spacecrafts' orbit and ensure the impact is scheduled to take place Friday morning, Dec. 14.

"Such a unique end-of-mission scenario requires extensive and detailed mission planning and navigation," said Lehman. "We've had our share of challenges during this mission and always come through in flying colors, but nobody I know around here has ever flown into a moon mountain before. It'll be a first for us, that's for sure."

During their prime mission, from March through May, Ebb and Flow collected data while orbiting at an average altitude of 34 miles (55 kilometers). Their altitude was lowered to 14 miles (23 kilometers) for their extended mission, which began Aug. 30 and sometimes placed them within a few miles of the moon's tallest surface features.

The published impact coordinates for the GRAIL twins has been well-surveyed by the Lunar Reconnaissance Orbiter Camera (LROC), at least nine times at high-resolution. LROC QuickMap 125 meter resolution [NASA/GSFC/Arizona State University].

JPL manages the GRAIL mission for NASA's Science Mission Directorate in Washington. The mission is part of the Discovery Program managed at NASA's Marshall Space Flight Center in Huntsville, Ala. Lockheed Martin Space Systems in Denver built the spacecraft. JPL is a division of the California Institute of Technology in Pasadena.